Iron and zinc are necessary for plant growth, carbon fixation and material production. Plants utilize the iron and zinc in soil by absorbing them.
However, there is little solubilized iron and zinc in the calcareous alkaline soil accounting for approximately 30% of soil worldwide, and the amount of solubilized iron therein is extremely low. Consequently, iron deficiency is a principal limiting factor with respect to plant growth in calcareous alkaline soil.
For this reason, it is an urgent task to acquire plants that grow satisfactorily even in poor soil, and especially in calcareous alkaline soil.
Plants which absorb iron and zinc from soil are principal supply sources of minerals for humans. As iron deficiency disorder and zinc deficiency disorder are grave problems for the world's population, and particularly for children and women, it would be desirable to acquire plants that contain copious amounts of iron and zinc in their edible parts.
In recent years, identification and analysis of genes that contribute to absorption and utilization of iron and zinc (particularly iron) have advanced. By altering such genes, and introducing them into plants, plants are being acquired that have improved iron and zinc deficiency tolerance, or which abundantly accumulate iron and zinc in their edible parts (see, e.g., Non-Patent Documents 1-11).